Re: regarding major number of block extended devt

[Tejun Heo <tj@kernel.org>]

Hello,

H. Peter Anvin wrote:
> Thinking about it some more, one invariant this is *guaranteed* to
> violate is:
> 
>     partition_number = partition_device - master_device
> 
> Code that needs a partition number (which is common enough) are using
> this invariant, because (a) it has held for 17 years and (b) because
> there is still no alternative other that relying on fragile naming
> scheme hacks.
> 
> (a) we can't do anything about, but (b) we can, by introducing a
> partition number attribute in sysfs.

Yeah, that would certainly be a nice addition.  Also, if partitions
are made proper classes, they'll be easily enumerable by
/sys/block/*/partitions/*.

Jens, what do you think?

-- 
tejun